File upload with Webdav

Hello,

we're using upload over WebDAV to Nextcloud with encryption. When sending bigger files (more than 20MB) it's getting an error 500, because checking if file exists after upload is before upload has finished, see logs below:

10.120.104.1 - rocket [02/Aug/2018:10:05:05 +0200] "GET /remote.php/webdav/AzXTGobezzwM968XN HTTP/1.1" 404 5 "-" "node-fetch/1.0 (+https://github.com/bitinn/node-fetch)"
10.120.104.1 - rocket [02/Aug/2018:10:05:06 +0200] "DELETE /remote.php/webdav/AzXTGobezzwM968XN HTTP/1.1" 404 5 "-" "node-fetch/1.0 (+https://github.com/bitinn/node-fetch)"
10.120.104.1 - rocket [02/Aug/2018:10:05:06 +0200] "DELETE /remote.php/webdav/AzXTGobezzwM968XN HTTP/1.1" 404 5 "-" "node-fetch/1.0 (+https://github.com/bitinn/node-fetch)"
10.120.104.1 - rocket [02/Aug/2018:10:05:06 +0200] "PUT /remote.php/webdav/AzXTGobezzwM968XN HTTP/1.1" 201 0 "-" "node-fetch/1.0 (+https://github.com/bitinn/node-fetch)"
10.120.104.1 - rocket [02/Aug/2018:10:05:06 +0200] "DELETE /remote.php/webdav/AzXTGobezzwM968XN HTTP/1.1" 204 0 "-" "node-fetch/1.0 (+https://github.com/bitinn/node-fetch)"

Locate the WebDAV upload implementation and reproduce the failure with an encrypted file larger than 20MB. Review the request sequence shown in the logs, then verify that completion checks and cleanup do not run before the upload finishes and that the upload no longer returns a 500 error.